Extract of by-products of the treatment of nuts and pulses, method for the production thereof and use of the same

ABSTRACT

The invention relates to an extract obtained from by-products of hard-shelled fruit and pulse processing characterised in that the by-products are selected from membranes and fruit residues of hard-shelled fruit, pulses or mixtures thereof, a method for producing the extract and its use as a colorant or additive, especially in foods, and for the production of coating films.

The present invention relates to an extract obtained from theby-products of hard-shelled fruit and pulse processing, a method for itsproduction and the use of the extract.

The wood, dark brown on the outside and blood-red inside, of thesandalwood tree (Pterocarpus santalinus), which is widespread in EastAsia and Africa, was earlier used for the dyeing of clothes and leather(Russia leather). Colorant components are santalin A, B and C, which areobtained by extraction using hexane, chloroform or ethanol (J. Verghese,Santalin—a peerless natural colorant, Cosmetics & Toiletries 1986, 101,69-74).

Depletion resulting from its increased industrial use (dye extracts,fragrance oils, cosmetic articles) means that the sandalwood tree is nowso rare that it is now a protected species (International Union ofConservation of Nature and Natural Resources [IUCN]: Red List Categoryand Criteria EN B1+2d, e). In addition, extracts from sandalwood cancause allergic skin reactions (A. Sandra, S. D. Shenoi and C. R.Srinivas, Allergic contact dermatitis from red sandalwood [Pterocarpussantalinus], Contact Dermatitis, 1996, 34, 69). Moreover, in discussionthey are regarded as not being completely safe in terms of health (seeJ. Verghese, Santalin, ibid.).

In spite of the problems described, sandalwood extract is normally usedtoday as a colorant in the snack industry since, compared with otherfood dyes, it has the technological advantage that it forms a film as itdries on the product, which prevents the adhesion of extrudates to eachother before the drying process.

Hard-shelled fruits are types of fruit in which the edible seed isenclosed by an inedible hard shell. These include nuts in particular.When hard-shelled fruits and pulses are processed, the by-productsinclude membranes and fruit residues. FR-A-2544593 relates to a foodthat is obtained from chopping up the fibrous parts of nuts.

The object of the present invention is to provide a suitable substitutefor sandalwood extract which also demonstrates the above-mentionedtechnological advantages and can be obtained from a raw material whichis available without limitation.

This object is solved according to the invention by an extract obtainedfrom by-products of hard-shelled fruit and pulse processing which ischaracterised in that the by-products are selected from membranes andfruit residues of hard-shelled fruit, pulses or mixtures of these. Thehard-shelled fruits are preferably nuts.

Examples of nuts of which the membranes and/or fruits can be used forthe production of the extract according to the invention includewalnuts, hazelnuts, peanuts, chestnuts, cashew nuts, almonds, brazilnuts and pistachios. Hazelnuts (genus: Corylus) are preferred; inparticular, hazelnuts from the hazel bush Corylus avellana L. cultivatedin northern climates are particularly preferred.

For use in foods, hard-shelled fruits, especially hazelnuts, aregenerally roasted without their shells. The associated browning of thehard-shelled fruits is influenced by the raw material composition, theroasting temperature, moisture content and pH value.

Large quantities of raw material are available, for example, as aby-product of the production of spreads for bread.

According to the invention, an extract is produced from the by-productsof the processing of hard-shelled fruits and pulses which are preferablyroasted.

As a particular preference, according to the invention, a red-brown,strongly coloured extract can be obtained through extraction fromby-products of hazelnut roasting (roasted seed shells [Lat. testa]). Thetypical dry matter content of the extract in unconcentrated form is inthe range of 0.1 to 20%, preferably in the range of 0.5 to 10%, and inparticular from 1 to 5%. After concentration, the dry matter content ofthe liquid extract is usually 10 to 30%, preferably 15 to 27%, and thedry matter content of the dry extract is usually 80 to 100%, preferably85 to 98%.

The raw extract usually contains minerals, proteins, fats, roughage andcarbohydrates in different quantities depending on the extractionconditions and quality of the raw materials.

The present invention also relates to a method for the production of theextract according to the invention, including the extraction of theby-products of the processing of hard-shelled fruits and pulses.

The extraction of the by-products of hard-shelled fruit and pulseprocessing can be carried out in stages or continuously; it ispreferably carried out in stages. Water or organic solvents may be usedas the extraction medium, alone or in various mixtures. Examples oforganic solvents include alcohols, such as methanol, ethanol, propanoland mixtures of these. Ethanol is used preferably as the organicsolvent. Water, if necessary in combination with alcoholic solvents,preferably ethanol, is particularly preferred. Particularly preferredare mixtures of water and ethanol in ratios from 70:30 to 30:70 (m/m).

Extraction is generally carried out at atmospheric pressure and attemperatures from 20 to 95° C., preferably from 30 to 80° C., andparticularly preferably from 40 to 70° C.

Extraction can be carried out with normal equipment in a known way.Extraction in stages can be carried out for example in a mashing tub orin a flow extraction plant.

Continuous extraction can be carried out for example by counterflowextraction, preferably in a carousel extractor.

The extraction of the by-products of hard-shelled fruit and pulseprocessing produces a raw extract which can be used in unconcentratedform, in an increased concentration or in dried form or is reprocessed,depending on the application. Reprocessing may include, for example,normal purification stages, such as decanting, centrifuging andfiltration, in order to separate out suspended matter.

The raw extract purified in this way can then be concentrated forexample by evaporation in order to produce a concentrated extract or adry extract. To produce a dry extract, the solvent can be removed fromthe raw extract, the purified raw extract or the concentrated extractfor example by spray drying, freeze drying or vacuum drying.

To produce the dry extract, usual adjuvants, such as carrier materials,can be added to the raw material.

Suitable carrier materials for the dry extract include carbohydratessuch as maltodextrin, glucose, modified starch, dextrin, saccharine andlactose, as well as lecithin, alginates, gum tragacanth, gum arabic,glucitol, pectins and cellulose derivatives. Water-soluble carriermaterials are preferred.

The dry extract can also be formulated, in particular with spray drying,with or without carrier material, according to the usual methods, as apowder or granulate that is stable in storage and easily dissolved inwater.

The extract according to the invention can be used as a colorant oradditive in both foods and non-foods. Both the raw extract and theconcentrated extract and dry extract are suitable for this.

The extract according to the invention can be used for example for thecolouring of foods, such as extruded and, if applicable, deep-friedsnack products, gelatine articles, hard caramels, milk products, drinkssuch as lemonades/carbonated drinks and fruit juice drinks, and bakedproducts such as bread, cakes and biscuits.

In addition, the extract according to the invention from by-products ofhard-shelled fruit and pulse processing is also suitable for use for thecolouring and/or coating of pharmaceutical preparations such as tablets,capsules and granulates.

The extract according to the invention can also be mixed with othercolouring extracts such as onion and/or malt extract in order to achievethe desired colour.

In the non-food sector, the extract according to the invention can beused for example in products in the paper or wood industry, inparticular as an additive or colorant.

The raw extract has a red-brown colour which is comparable to the colourstrength of caramel (colorant E150d) (definition according to Directive95/45 EC, 07/26/95). Its colorant qualities can be varied from yellow,orange, red, red-brown to dark brown by changing the pH and the dosagein the range from 1 to 14.

In addition, the extract according to the invention is suitable, becauseof its extraordinary heat and light stability, as a substitute foranthocyan-based, carmine-based and synthetic colours at an acid pH, andfor carmine-based and synthetic colours also at a neutral pH. Theallergenic potential of the extract according to the invention isextremely low. The extract is hypoallergenic.

It was also found that the extract according to the invention obtainedfrom by-products of hard-shelled fruit and pulse processing canstabilise anthocyans and/or anthocyanidins. In particular, the extractaccording to the invention can stabilise anthocyans and/oranthocyanidins to prevent decomposition under the influence of light.

Anthocyans are a group of chemically related blue, violet and redcolorants (benzopyrylium salts), very common in the plant world, whichare dissolved in the cellulose of blossoms and fruits and occasionallyalso in sprout axes and leaves of plants and which create the colouringsthat typify these. In chemical terms, anthocyans are glycosides of theactual chromophores, the anthocyanidins.

All the known anthocyanidins have as their basic structure the C-4′hydroxylated 2-phenyl chromene (shown in the primary structure asflavylium cation):

The anthocyanidins are derived from three basic structures:pelargonidin, cyanidin and delphinidin, which differ from each otherthrough their different substitution in the B-ring. In addition,3-desoxyanthocyanidins are also known (see, e.g., Römpp Lexikon Chemie,10th edition, 1996-1999, p. 210-212).

Examples of anthocyanidins which occur in many different plants andplant parts include pelargonidin, cyanidin, delphinidin, apigenin,paeonidin, petunidin, malvidin, hirsutidin and tuberidin.

The extract according to the invention can considerably improve thelight stability of the listed anthocyans and anthocyanidins.

Preferably, the extract according to the invention is used for improvingthe light stability of juices and/or juice concentrates from fruits andvegetables containing anthocyan and/or anthocyanidin, such as:blackcurrants, cherries, elderberries, aronia berries, red grapes,hibiscus, black carrots, red cabbage, purple potatoes and sweetpotatoes.

The extract according to the invention obtained from by-products ofhard-shell fruit and pulse processing is extremely strongly coloured,stable in storage, fast-drying, stable in deep-frying and represents anoutstanding substitute for sandalwood extract, which is expensive anddifficult to obtain, particularly because the extract according to theinvention presents not only colouring but also film-forming propertieswhich are comparable with those of the sandalwood extract. That meansthat the extract according to the invention obtained from by-products ofhard-shell fruit and pulse processing dries like the sandalwood extracton surfaces, especially starch pellets, quickly and forms a film, whichis crucial for its application on food surfaces and other particlesurfaces, since the adhesion of particles is prevented. The extractaccording to the invention has the advantage over sandalwood extractthat it is still stable in the lower pH range below 5 and that it isobtained from cheap raw materials which are available withoutlimitation.

EXAMPLE 1

13 g roasted hazelnut membranes are mixed with 150 g water and 30 gethanol (94.6% by mass) and stirred for 2 hours at 75° C. Afterseparation of the pomace, the resulting raw extract is filtered using afluted filter. Through evaporation using a rotation evaporator, 10 g ofextract concentrate with 25.2% dry matter (according to Art. 35 LMBG(German Food and Commodities Law) L 03.00-9) was obtained.

EXAMPLE 2

140 g invert sugar syrup, 14 g citric acid solution (50%), 0.15 gascorbic acid were filled to 1000 g with demineralised water. The mediumwas kept at a temperature of 23° C. and set to a pH of 3.00 with NaOHsolution (50%). A 702 SM Titrino (Metrohm, Herisau, Switzerland) with aglass electrode was used to measure the pH. The extract according to theinvention from Example 1 was added to the resultant lemonade-type mediumwith the addition of ascorbic acid and was easily dissolved by stirring.As shown in FIG. 1, the colour shades yellow, orange, red and brown wereproduced depending on the dosage (0.01, 0.05, 0.1, 0.25% by mass).

EXAMPLE 3

The stability of the following colour extracts was examined under theinfluence of light in a lemonade-type medium with added ascorbic acidaccording to Example 2:

-   -   1 The extract according to the invention as in Example 1    -   2 Anthocyan-based red-yellow vegetable colour extract    -   3 Anthocyan-based red-blue fruit colour extract    -   4 Carmine-based colour extract, E120    -   5 Synthetic dye azorubin, E122

For this, the dilution of the colour extracts in the lemonade-typemedium with the addition of ascorbic acid was chosen in such away that,for all the samples to be examined, a red colouring occurred in the areaof an a* value of 44.3±0.5 (according to the ClE-L*a*b* system).

7 clear polystyrene Accuvettes (Beckmann Coulter GmbH, Krefeld; height:5.6 cm, wall thickness: 1 mm, internal diameter: 30 mm, volume: 27 ml)were each filled with 25 ml of sample. The filled Accuvettes were placedin a temperature-maintained stainless steel tub in the floor of thelight chamber of the Suntester lighting device (Atlas Suntester CPS,xenon lamp, 765 W/m², daylight filter: filter dish 65052381). Awater/ethanol mixture (90/10, v/v) was used as thetemperature-maintenance medium. The thermostat temperature was 23° C. Atthe beginning t₀ and after every hour t₁ . . . t₆, the colour valueswere measured with a Lico 200 spectrophotometer (Dr. Lange GmbH & Co.KG, Düsseldorf).

FIG. 2 shows the extraordinary light stability of the extract accordingto the invention from Example 1 in a lemonade-type medium with addedascorbic acid. In comparison with other colour extracts, the extractaccording to the invention shows, in the example named, the highestred-shade stability (a* value) under the influence of light.

EXAMPLE 4

The stability of the following colour extracts in a lemonade-containingmedium with added ascorbic acid under Example 2 was examined under theinfluence of heat:

1 The extract according to the invention as in Example 1

2 Anthocyan-based red-yellow vegetable colour extract

3 Anthocyan-based red-blue fruit colour extract

4 Synthetic dye azorubin, E122

For this, the dilution was selected in such away that, for all thesamples to be examined, a red colouring occurred in the area of an a*value of 45.3+0.5. 6 closable reagent glasses (12 ml volume) were eachfilled with 10 ml of the sample and placed in a water bath at 90° C.(pasteurisation conditions). At the beginning, and after 1, 3, 5, 7 and10 minutes, the colour values (according to the CIE L*a*b* system) weremeasured with a Lico 200 spectrophotometer (Dr. Lange GmbH & Co. KG,Düsseldorf).

FIG. 3 shows the extraordinary heat stability of the extract accordingto the invention from Example 1 in a lemonade-type medium with addedascorbic acid. In comparison with other colour extracts, the extractaccording to the invention shows, in the example named, the highestred-shade stability (a* value) under the influence of heat.

EXAMPLE 5

In an investigation of the extract concentrate from Example 1, acompetitive ELISA test only showed very small quantities of theallergenic hazelnut protein (37+10 mg/kg).

For example, in the application of the extract concentrate from Example1 as a colorant for deep-fried snacks (concentration: 0.05% by mass),the estimated daily consumption of hazelnut protein is, because of thelow dosage, well below the limit of 720 μg assumed to trigger allergies(I. Malmeheden Yman et al., Analysis of food proteins for verificationof contamination or mislabelling, Food Agric. Immunol., 1994, 6,167-172; The little “Souci-Fachmann-Kraut” Food Table for practical use,WVG, Stuttgart, 1991). In order to reach the critical threshold valuerequired to trigger an allergic reaction, between 37 and 64 packs (of 75g each) of this product would need to be eaten.

The danger of triggering an allergic reaction for example by theconsumption of a deep-fried snack product coloured with the extractconcentrate from Example 1 is therefore relatively minor.

EXAMPLE 6

100 g roasted hazelnut shells were mixed with 500 g ethanol (94.6% bymass). The mixture was stirred for 2 hours at 20° C. After separation ofthe pomace, the resulting raw extract was filtered using a flutedfilter. Through evaporation using a rotation evaporator, 10 g of dryextract in powder form (95% dry matter) was obtained.

In a photometric determination according to Folin-Ciocalteu (V. L.Singleton et al., Analysis of total phenols and other oxidationsubstrates and antioxidants by means of Folin-Ciocalteu reagent, Methodsin Enzymology, 1999, 299, 152-178), the total phenol content, calculatedas gallic acid (Fluka Chemie GmbH, Buchs, Switzerland), is equivalent to8.34% in relation to the dry matter.

EXAMPLE 7

1 g of the powder obtained by spray drying of the hazelnut extract wasdissolved in 100 ml demineralised water. 1 l of the lemonade medium(made according to Example 2) was added to 0 ml (reference), 2.2 ml(mixture A), 6.6 ml (mixture B), 11 ml (mixture C) of the redissolvedhazelnut extract and coloured with 1 g elderberry juice concentrate. Thelight stability was compared as described in Example 3.

FIG. 4 shows that the addition of hazelnut extract powder in thequantity of mixture B and C can lower the red shade loss of the lemonadecoloured by elderberry by around ⅓ after 5 hours in the Suntester.

1. Dry extract obtained from roasted by-products of hard-shelled fruitand pulse processing, whereby the by-products are membranes and/or fruitresidues of hard-shelled fruits, pulses or mixtures thereof.
 2. Dryextract according to claim 1, wherein said hard-shelled fruits are nuts.3. Method for production of the dry extract according to claim 1,comprising the extraction of the by-products of hard-shelled fruit andpulse processing and drying of the extract.
 4. Method according to claim3, wherein the extraction is carried out in stages.
 5. A method ofcoloring a product comprising the addition of the dry extract of claim 1to the product.
 6. A method to stabilise anthocyans and/oranthocyanidins comprising adding the dry extract of claim 1 to a productcontaining said anthocyans and/or anthocyanidins.
 7. The method of claim5, wherein said product is a food.
 8. A method to form a film comprisingapplying said dry extract of claim 1 to a substrate to form said film.9. A food product comprising the dry extract of claim
 1. 10. The dryextract of claim 2, wherein said nuts comprise walnuts, hazelnuts,peanuts, chestnuts, cashew nuts, almonds, brazil nuts, pistachios, or acombination thereof.